Apparatus for applying high viscosity mixture of reactive components

ABSTRACT

A greatly simplified apparatus for mixing and dispensing a high viscosity mixture of reactive components, such as the components of a urethane-based adhesive. The apparatus consists essentially of an elongated hollow member having an input end and an output end, the member defining a mixing chamber and terminating in a nozzle at its output end. A mixing means is located within the hollow member and acts in cooperation therewith such that, after the first and second reactive components pass through the hollow member under pressure, the reactive components comprise a generally homogeneous mixture. A body member is fixedly mounted to the input end of the hollow member and is adapted to have a plurality of valves mounted thereto. There is a first valve and a second valve mounted on the body member, the first valve having an inlet and a pressurized source of the first reactive component connected thereto, the second valve having an inlet and a pressurized source of the second reactive component connected thereto. Each of the valves has an outlet in permanent, open communication with the mixing chamber by means of a passageway through the body member such that during intermittent stopping and starting of the flow of the components and the mixture, a smooth-walled, continuous flow path is presented to the materials, thus greatly reducing the possibility of build-up of hardened materials within the gun.

ljriit tates Patet [191 Mar. 5, 1974 APPARATUS FOR APPLYING HKGHVlSCOSlTY MIXTURE 0F lilEACTlVE COMPONENTS [75] Inventor: Ronald D.Kattner, North Canton,

Ohio

[73] Assignee: The General Tire & Rubber Company, Akron, Ohio Filed: May25, 1973 Appl. No.: 356,004

Primary Examiner-Lloyd L. King [5 7] ABSTRACT A greatly simplifiedapparatus for mixing and dispensing a high viscosity mixture of reactivecomponents,

such as the components of a urethane-based adhesive. The apparatusconsists essentially of an elongated hollow member having an input endand an output end, the member defining a mixing chamber and terminatingin a nozzle at its output end. A mixing means is located within thehollow member and acts in cooperation therewith such that, after thefirst and second reactive components pass through the hollow memberunder pressure, the reactive components comprise a generally homogeneousmixture. A body member is fixedly mounted to the input end of the hollowmember and is adapted to have a plurality of valves mounted thereto.There is a first valve and a second valve mounted on the body member,the first valve having an inlet and a pressurized source of the firstreactive component connected thereto, the second valve having an inletand a pressurized source of the second reactive component connectedthereto. Each of the valves has an outlet in permanent, opencommunication with the mixing chamber by means of a passageway throughthe body member such that during intermittent stopping and starting ofthe flow of the components and the mixture, a smooth-walled, continuousflow path is presented to the materials, thus greatly reducing thepossibility of build-up of hardened materials within the gun.

14 Claims, 5 Drawing Figures ill til l l l PAIENTED 51974 $795364 sum 20F 3 FIG. 2

APPARATUS FOR APPLYING HIGH VISCOSITY MIXTURE F REAQITIVE COMPONENTSBACKGROUND OF THE DISCLOSURE 1. Field of the Invention This inventionrelates to the mixing and application of several reactive components,and more particularly, to an apparatus for mixing and dispensing highviscosity materials such as polymeric resins.

While the present invention is equally useful for mixing and applyingany high viscosity materials, it is especially advantageous when used tomix the components of urethane-based adhesives, and will be discussed inconnection therewith. The availability of polymeric adhesives has playedan important role in the development of markets for fiber-reinforcedplastic (FRP) materials, because FRP parts can be readily andpermanently bonded to each other or to other materials by polymericadhesives, and especially the urethane-based adhesives. Such adhesiveshave also been used successfully to bond parts made of steel, aluminum,other plastics and even wood, to another part of either similar ordissimilar material.

The selection of urethane-based adhesives over other adhesives is basedpartlyon their outstanding characteristics with respect to bondstrength, chemical inertness, tensile strength and handling.

' 2. Description of the Prior Art Although the use of the conventionalurethane-based adhesives is generally advantageous, one problem whichhas arisen is that, although highly viscous, they tend to run off ordrip down inclined or overhead surfaces prior to solidification. This ofcourse results in bare spots where no bonding occurs and impairs theultimate strength of the bond.

This problem has resulted in the development of improved urethaneadhesives which substantially eliminate the run-off problems, but whichare even more viscous, frequently reaching a viscosity of about 100,000cps. or more immediately after the components are mixed. See, forexample, U.S. Pat. No. 3,714,127 assigned to The General Tire & RubberCo.

The typical prior art apparatus for mixing and dispensing such materials(generally referred to as mixing guns) was primarily adapted forapplying or spraying liquid adhesives, and other resinous materialsgenerally in the viscosity range of about 2,000 to about 10,000 cps.

Much of the prior art in regard to mixing guns actually relates to sprayguns which rely for their operation on high pressure air to expel themixed liquid components in atomized or droplet form, such as U.S. Pat.Nos. 3,035,775 and 3,122,322. It is apparent that such spray deviceswould not be operable formixing and applying a high viscosity materialsuch as an adhesive,

having approximately the consistency and flowability of toothpaste. Inaddition, during mixing of the components of a urethane-based adhesive,the presence of air in the mixing chamber cannot be tolerated, becausethe air and the moisture in the air ruin the mixture physically byfoaming it, thus making the mixture unsuitable for subsequentapplication as an adhesive.

The prior art also shows mixing guns which do not use an air spray andhence are referred to as airless mixing guns. Some airless guns, such asis shown in U.S. Pat. No. 2,890,836, do not include a mixing device,relying instead on a vortexflow of the components for complete mixing,and their use is therefore limited to liquids or components of extremelylow viscosity. in many other airless mixing guns, the flow path of oneor more of the components passes through such elements as: spring biasedcheck valves (U.S. Pat. Nos. 3,123,306, 3,338,561, 3,417,923 and3,437,273) valve cylinders with circumferential inlet and outlet ports,much smaller than the feed lines (U.S. Pat. No. 3,708,123), and variousother arrangements of small passageways and miscellaneous impedances tothe flow of the reactive components (U.S. Pat. Nos. 3,176,922, 3,116,878and 3,304,010).

The complicated passageways and valve arrangements in the prior artmixing guns result in several serious operating problems when such gunsare used for mixing high viscosity reactive components which tend toset-up or harden within a very short time. The major problem duringoperation is the tendency for the prior art mixing gun to form abuild-up of either the adhesive or one of the reactive components whichhas hardened. The tendency to build-up is greatest around valves,springs, and other discontinuities in the flow path. A related problemis that after some of the adhesive or one of the components forms ahardened build-up within the mixing gun, particles of the hardenedmatter may break loose and become mixed-in with the fresh adhesive whichis subsequently applied to form a bond. Previously cured particles ofmaterial in the fresh adhesive have the same effect as voids in theadhesive layer and the result is a point at which no bond occurs betweenthe mating surfaces, and an overall weakening of the bond. Occasionally,especially in the guns in which either the components or the mixedadhesive must follow a relatively long flow path through the gun, theparticular material may harden within the passageway, thus completelystopping the flow of that particular material. If a build-up occurs inthe area of a discontinuity, such as a valve or spring, or if there is arestriction in the passageway caused by a hardening of some of thecomponent, the result will be a reduction in the propor tion of thatparticular component in the mixture, with a possible impairment of thebonding ability of the mixture.

Certain problems have arisen also in regard to maintaining the prior artmixing guns. It has been found to be quite difficult to clean or flushthe complex prior art mixing gun. Flushing and cleaning are generallyaccomplished by means of a solvent such as methylene chloride. When theflow paths and passageways within the gun are relatively long andcomplex, the methylene chloride flush is frequently unable to adequatelydissolve and remove the old material from the passageways of the gunbecause the flushing fluid has a tendency to wear-out" before the entiregun is cleaned. With a typical prior art gun formerly used to apply aurethane-based adhesive, it has been found that, on the average, the gunmay be operated for only about half a working shift before it must becompletely disassembled and cleaned with methylene chloride. Because ofthe large number of valves, springs, O-rings and seals in thisparticular gun, the entire disassembly, cleaning and reassemblyoperation may take several hours. Thus, many extra guns are needed forthe operation, and the maintenance costs greatly increase the overallcost of using such guns.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide a mixing gun for use with high viscosity componentswhich substantially eliminates the problems discussed above.

More specifically, it is an object of the present invention to provide amixing gun in which the flow path of each of the reactive components, aswell as of the mixed adhesive, is relatively short and has a minimum ofobstructions and discontinuities which can cause the flowing material toplug the passageway or leave a partial build-up.

It is a further object of the present invention to provide a mixing gunwhich substantially eliminates all small, intricate parts which tend toobstruct the flow of material in the gun and provide a place for abuild-up of hardened materials to form.

It is a related object of the present invention to provide a mixing gunin which there are no valves, along the path of any of the materials,which are operating while the flow of the material is intermittentlystopping and starting.

It is also an object of the present invention to provide a mixing gunwhich can be readily cleaned by flushing with solvent, withoutdisrupting the use of the gun, or necessitating disassembly of the gun,removal of lines or temporary connection of additional lines.

It is another object of the present invention to provide a mixing gunwhich can be quickly and easily disassembled, thoroughly cleaned andreassembled in a relatively short time and with little or no chance of apart being put back improperly.

These and other objects of the present invention, which will becomeapparent upon a reading of the following detailed description, areaccomplished by the provision of apparatus for mixing a first reactivecomponent and a second reactive component and applying the mixture. Theapparatus consists essentially of:

a. an elongated hollow member having an input end and an output end, themember defining a mixing chamber and terminating in a nozzle at itsoutput end;

b. mixing means located within the hollow member and acting incooperation therewith such that, after the first and second reactivecomponents pass through the hollow member under pressure, the reactivecomponents comprise a generally homogeneous mixture;

c. a body member fixedly mounted to the input end of the hollow memberand adapted to have a plurality of valves mounted thereto;

d. a first valve and a second valve mounted on the body member, thefirst valve having an inlet and a pressurized source of the firstreactive component connected thereto, the second valve having an inletand a pressurized source of the second reactive component connectedthereto;

e. each of the valves having an outlet in permanent, open communicationwith the mixing chamber, by means ofa passageway through the bodymember.

In accordance with a further aspect of the present invention, theapparatus includes a third valve mounted on the body member, having aninlet and pressurized source of a solvent fluid connected thereto, thethird valve having an outlet in permanent open communication with themixing chamber, by means of a passageway through the body member,whereby the mixing chamber can be flushed with solvent fluid withoutdisassembling any portion of the apparatus and without the necessity oftemporarily attaching additional lines to the apparatus.

The objects of the present invention are further accomplished by theprovision of an improvement in the method of mixing a first reactivecomponent and a second reactive component and dispensing the resultinghighly viscous polymer mixture, the method including pumping the firstreactive component from a first storage container to the mixing gun,pumping the second reactive component from a second storage container tothe mixing gun, admitting the first and second reactive components intothe mixing gun, mixing the reactive components and dispensing thepolymer mixture. The improvement comprises:

a. providing a first connecting means such that the first storagecontainer is in open communication with the mixing gun;

b. providing a second connecting means such that the second storagecontainer is in open communication with the mixing gun;

0. simultaneously actuating the pumping means on the first storagecontainer and the pumping means on the second storage container, therebyforcing the first and second reactive components directly into themixing gun;

d. simultaneously de-actuating the pumping means on the first storagecontainer and the pumping means on the second storage container when thedesired amount of the polymer mixture has been dispensed.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of the adhesive gunof the present invention, with all incoming lines removed;

FIG. 2 is a cross-section of the present invention on approximately thesame scale as FIG. 1;

FIG. 3 is a cross-section, taken on line 3--3 of FIG FIG. 4 is across-section taken on line 4-4 of FIG.

FIG. 5 is an enlarged cross-section of a typical ball valve used withthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Adhesive Gun Referringspecifically to the drawings, which are for the purpose of illustratingthe preferred embodiment of the present invention and not for limitingthe same, FIG. 1 is a perspective in which the adhesive gun isdesignated generally by the numeral 10. The gun is divided generallyinto a chamber portion 20 and a body portion 60. The valves andauxiliary equipment will be described subsequently.

Turning now to FIG. 2, which, in the subject embodiment is both avertical section and a horizontal section of the adhesive gun, but willbe treated subsequently as a vertical section, the simplicity of thedesign of the present invention is apparent.

Chamber portion 20 comprises a generally elongated, hollow member 22,which defines the mixing chamber. The member 22 has internal threads 24at its input end such that the member 22 and the body portion 60 can bethreadedly connected. Chamber portion 20 terminates at its output end ina portion 26, gradually tapering from the larger diameter of the member22 to the relatively smaller nozzle-defining portion 28, through whichthe substantially homogeneous mixture of reactive components passes.

Within the mixing chamber 30 is a mixing device which, in the subjectembodiment, comprises a sleeve 32 with 4 longitudinal rows ofradially-inwardlyprojecting studs 34', as can best be seen in FIGS. 2and 4. It should be noted however that in FlG. 4 the rotating mixingmember 36 has been displaced 45 from the position shown in FIG. 2, forpurposes of clarity. The

rotating mixing member 36 includes 4 rows of axially, uniformly spacedvanes 38 which extend radially outward from the central backbone 40, andare arranged so as to pass between the studs 34.

Preferably, the heads of the studs 34 conform to the frusto-conicalbores in the sleeve 32 which may then be press fit into the member 22.It may be desirable to braze or weld over the heads of the studs 34 toinsure that they are positioned solidly with respect to the sleeve 32,and it may alternatively be desired to braze or weld the sleeve 32 intothe member 22 rather than relying on a press fit. In either case, theaxial alignment of the sleeve and stud assembly is important inrelationship to the bearing surface 42, at the output end of the mixingchamber, to be sure that there is no interference between the mixingvanes 38 and the studs 34. For this reason, it is preferable that hollowmember 22 be a single piece, rather than having the tubular portionsurrounding sleeve 32 as one piece and portion 26 as a separate piece.

It should be clearly understood that the adhesive gun of the presentinvention is in no way dependent upon the particular mixing device whichis used for mixing the reactive components. It is not even strictlynecessary that the mixing occur by means of meshing mixing elements inwhich one is stationary and the other rotates, although such anarrangement seems preferable.

Body member 60 is shown as being threadedly connected to the chamberportion 20 by means of threads on the outside of hub portion 62. Bodyportion 60 defines a central bore 64 through which passes a shaft 66 forthe purpose of driving rotating mixing member 36, to which the shaft 66is connected by any one of a number of well-known means such as the fourlugs 68, with one positioned on each side of each vane 38, at the inputend of the rotating mixing device 36.

The primary purpose of body portion 60 is to provide (1) means forsealing the end of chamber portion 20 so that no air can enter themixing chamber; (2) alignment means for the rotating mixing member; (3')locating and attaching means for the lines carrying the variouscomponents; and (4) passageways between the incoming lines and themixing chamber. The arrangement of valves and passages can best be seenby looking at FIG. 3 in conjunction with FIGS. 2 and 1 (with the valve100 cut-away so as not to hide shaft 66). By way of example, ball valve100, which in the subject embodiment is connected to the catalyst (orhardener) line, is threaded into orifice 102, which intersects at rightangles bore 104, which in turn feeds passageway 106, emptying into themixing chamber. The bore 104, is preferably drilled inwardly fromsurface 108, and must be capped during operation of the gun, such as bya threaded plug similar to plug 119 capping bore H4 in FIG. 3. Inaddition to valve for the hardener, there is also a valve for the resin(or base), a valve for the solvent,.and a valve for air. It should beapparent that within the scope of the present invention, more than tworeactive components can be mixed by adding another valve and passagearrangement similar to that described above for the catalyst (valve100).

For simplicity, the drive means for turning shaft 66 and rotating mixingmember 36 is not shown, and it should be clearly understood that theinvention in no way depends upon the particular type of drive used.Probably the most convenient and economical drive is an air motor,either connected directly to the shaft 66, and mounted on body member 60or positioned remotely from the adhesive gun and connected to shaft 66by means of a flexible drive shaft. The choice between the flexibledrive shaft and the direct drive may be based upon the viscosity of thematerials being mixed, as a flexible shaft may not be able to turn themixing device 36 through the most viscous materials. Also not shown inthe Figures is the apparatus which includes temporary storage tanks forthe resin, hardener'and flush solvent, as well as the pumping apparatusfor each. With the mixing gun of the present invention, any one of anumber of commercially available storage and pumping systems may beused. Whereas the complexity of the prior art mixing guns limited theviscosity of the reactive components, the adhesive gun of the presentinvention does not present such a limitation and theviscosity of thereactive components is now limited only by the pumping capability of thecontainer-and-pumping system.

in order to obtain the maximum benefit from the smooth, free-flowingdesign of the adhesive gun of the present invention, the valves, andespecially resin valve 110 and catalyst valve 100 are preferably of thetype shown in H6. 5. Merely by way of example, the illustrated valve isindicated as being the catalyst valve MN). The valve 100 includes a ball101 which can move only by rotation about its major diameter,perpendicular to the plane of the figure. The ball 101 defines apreferably cylindrical bore 103 which, in the operating position shownin FIG. 5 is axially alligned with, and substantially the same size as,the valve bore 105. Thus, the valve 100 present a generallysmooth-walled, continuous path of flow for the material. In addition tothe ball bore 103 and valve bore 105 being the same diameter,

- it is preferable that the incoming resin line and hardener'line, aswell as the bores and passages through body portion 60, have the samediameter also, so that no part of the flow path presents a restrictionto the flow of material.

The ball 101 may be rotated by means of valve handle 107, pivotallyattached to ball 101. For simplicity, no handles are shown on the valvesin the other figures, although it will be apparent that some form ofactuation means is needed for the valves. The ball 1011 may have a seal109 between the ball and its seat, the seal being made from a materialsuch as that sold by du Pont under the trademark TEFLON.

Referring again to chamber portion 20, and body portion 60, both'partscan be machined from tool steel or coldrolled steel, but preferably,aluminum may be used to reduce the weight of the gun, especially if itis to be hand-held by an operator. The same basis for material selectionapplies to the internal mixing parts. Operation As was mentionedpreviously, the container and pumping system usable with the presentinvention may be any of those commercially available and capable ofgenerating sufficient pumping force. The pumping system shouldpreferably be arranged such that the pump for the resin and the pump forthe hardener are actuated and de-actuated together. The control meansfor the pumps may be a valve or a switch located either at the pumps orsomewhere on the adhesive gun itself. In operation, the valve handlesfor both the resin (handle not shown) and the hardener (handle 107) areturned to the open position illustrated in FIG. and the resin pump,hardener pump and drive means for shaft 66 can then be actuated,possibly by a single actuation means. The resin flows through valve 110,orifice 112, bore 114 and passage 116 (not shown), and into the mixingchamber 30, while simultaneously, the hardener flows through valve 100,orifice 102, bore 104, passage 106 and into mixing chamber 30. Up tothis point, neither reactive component has encountered anything toobstruct its smooth flow path. The two reactive components are thencombined as a homogeneous mixture in the mixing chamber as previouslydiscussed, and expelled through nozzle 28. Each of the reactivecomponents, as well as the mixture of the two is forced through theline, the valves, the body portion, the mixing chamber and the nozzlesolely by the force of the pumps.

When a sufficient amount of the adhesive (or other material) has beenmixed and dispensed, the resin and hardener pumps may be de-actuated tostop the flow of materials and the drive means for shaft 66 can also beturned off while the operator moves to the next work station, or untilthe next set of pieces to be bonded is brought to the operator. If theadhesive gun will be operated again within a period of time which isfound experimentally to be less than the set-up time of the mixture,valves 100 and 110 can be left open. If the time lapse before the nextuse of the gun is greater than the set-up time, however, valves 100 and110 should be closed and the gun flushed as will be describedsubsequently. Depending upon the proposed use for the mixing gun, it maybe desirable to eliminate the valves 100, 110 for the hardener andresin, respectively, so that the mixing chamber is permanently in opencommunication with the storage containers for the resin and hardener. Ifthis is done, however, it may be desirable to provide aquick-connect-disconnect between each line and the mixing gun tofacilitate cleaning without getting air and solvent into the resin andhardener lines. Cleaning Cleaning the adhesive gun of the presentinvention can involve either flushing quickly with a solvent such asmethylene chloride, then drying with air, or disassembly of the gun andthorough cleaning of the parts in a bath or container ofthe solvent. Inthe situation described above wherein the gun will not be operated for aperiod of time greater than the set-up time of the material, the gunshould be flushed with solvent by first closing the resin valve 110 andthe hardener valve 100 to prevent either the solvent or air from gettinginto the lines and mixing with the reactive components. Next, methylenechloride or some other suitable solvent is admitted into the mixing gunby opening valve 120 (see FIG. 1) to a position such as is illustratedin FIG. 5. The methylene chloride then passes through orifice 122, bore124 and passage 126 (not shown), then into mixing chamber 30. As thesolvent passes through the mixing chamber under the force of its pump,the mixing device 36 may preferably be made to rotate, to aid inthoroughly cleaning the adhesive mixture out from between the studs 34and mixing vanes 38. During flushing it is of course necessary to have acontainer near the nozzle to collect the mixture of solvent anddissolved adhesive material expelled from the gun. After about 5 or 10seconds of flushing, substantially all of the adhesive should be out ofthe mixing chamber, so that only solvent is coming out of the gun. Whenthis occurs, solvent valve should be closed and air valve 130 opened toallow air to pass through orifice 132, bore 134, passage 136 (see FIG.2), and through mixing chamber 30, to dry the solvent remaining in themixing chamber. The gun can then be left in this clean, shutdowncondition (i.e., all four valves closed), for a relatively long periodof time before recommencing use of the gun. What is meant by a longperiod of time depends upon the particular materials being used, but itwould be common practice for the operator to leave the gun in theshut-down position described during a half-hour or hour lunch period,whereas it would normally be necessary to disassemble and clean the gunafter it has been out of use overnight or for an entire work shift.

It can be readily appreciated from viewing FIGS. 2, 3 and 5 that becauseof the smooth flow path through the valves and passageways of the bodyportion 60, the flow paths for the resin and hardener are keptrelatively clean merely by the normal operation of the gun. Therefore,instead of totally disassembling the gun and soaking all of the variousparts, valves, springs, etc. as has been done with the prior art mixingguns, it is possible to thoroughly clean the adhesive gun of the presentinvention periodically (such as during a shift when the gun is not beingused), by unthreading the chamber portion 20 from the body portion 60.When this is done, the mixing device 36 will become disengaged from thelugs on the end of shaft 66, and the two pieces so removed, the member22 and the mixing device 36 can then be thoroughly cleaned by soakingthem in a solvent such as the methylene chloride used to flush the gun.While merely flushing the gun will almost always keep it sufficientlyclean for normal operation, it should be noted that in the eventparticles do build up in the mixing chamber, the simplified design andconstruction of the subject embodiment permits disassembly, removal ofthe particles, and reassembly within as l ttl a 999 1t9animate.-. .1-

While the adhesive gun of the present invention is normally intended foruse as a portable, hand-held mixer and dispenser, with the resin and thehardener containers and pumps preferably mounted on a portable dolley,it should be clearly understood that it is within the scope of thepresent invention to mount such a mixing gun as a permanent part of asemi-automated or fully-automated assembly jig or fixture. If such anarrangement were desired, the mixing gun may be fixed to a movable arm,which can automatically follow any desired bead pattern, with theactuation means for the resin and hardener pumps and the drive means forthe mixing device being operated as part of an automatic cycle. Inaddition, the solvent flushing procedure for the gun could occurperiodically (for example, once every four cycles), during the curingportion of .the

bonding cycle when the gun is not mixing and dispensing.

Thus, it is apparent that the present invention provides a mixing gun inwhich the flow path of each of the reactive components, as well as ofthe mixed adhesive, is relatively short, and has a minimum ofobstructions and discontinuities to cause the flowing material to plugthe passageways or leave a partial build-up. Also, the present inventionprovides a mixing gun which can be readily cleaned by flushing withsolvent, without disrupting the use of the gun, or necessitatingdisassembly of the gun, removal of lines or temporary connection ofother lines. I

While the invention hasbeen described in great detail sufficient toenable one vof ordinary skill in the art to make and use the same,alternatives and modifications of the preferred embodiment will occur toothers upon a reading of the specification. It is intended that all suchalternatives and modifications be included within the present inventionin so far as they come within the scope of the appended claims.

What is claimed is: n

1. Apparatus for mixing a first reactive component and a second reactivecomponent and applying the mixture, said apparatus consistingessentially of:

a. an elongated hollow member having an input end and an output end,said member defining a mixing chamber and terminating in a nozzle atsaid output end;

v b. mixing means located within said hollow member and acting incooperation therewith such that, after the first and second reactivecomponents pass through said hollowmember under pressure, the reactivecomponents comprise a generally homogeneous mixture;

c. a body member fixedly mounted to said input end of said hollow memberand adaptedto have a plurality of "valves mounted-thereto; r

d. a first valve and a second valve mounted on said 4. The apparatus ofclaim 1 wherein said valves are ball valves in which the ball defines acylindrical bore, of substantially the same diameter as said inlet boreand said outlet bore such that the valve provides a generallysmooth-walled, continuous path of flow for the reactive component.

body member, said first valve having an inlet bore and a pressurizedsourceof the first reactive component connected thereto, said secondvalve having an inlet bore and a pressurized source of the secondreactive component connected thereto;

e. each of said valves having an outlet bore in permanent, opencommunication with said mixing chamber, by means of a passage-waythrough said body member.

2. The apparatus of claim 1 wherein said mixing means is rotatablymounted within said mixing'chamher and is driven by an external drivemeans connected to said mixing means by a sealed shaft, such thatsubstantially no airv is allowed to enter said mixing chamber duringmixing.

3. The apparatus of claim 1 including a third valve mounted on said bodymember, having an inlet bore solvent fluid without disassembling anyportion of said 6 apparatus and without the necessity of temporarilyattaching additional lines or equipment to said apparatus.

5. The apparatus of claim 4 wherein said valves are operable to havesaid cylindrical bore oriented axially with said inlet bore and saidoutlet bore and maintain said orientation as the reactive component isintermittently pumped through said valve.

6. In a method of mixing a first reactive component and a secondreactive component and dispensing the resulting highly viscous polymermixture, the method including pumping the first reactive component froma first storage container to the mixing gun, pumping the secondreactivecomponent from a second storage container to the mixing gun,admitting the first and second reactive components into the mixing gun,mixing the reactive-components and dispensing the polymer mixture, theimprovement comprising:

a. providing a first connecting means such that the first storagecontainer is in open communication with the mixing gun;'

' b. providing a second connecting means such that the second storagecontainer is in open communication with the mixing gun;

c. simultaneously actuating the pumping means on the first storagecontainer and the pumping means on the second storage container, therebyforcing the first and second reactive components directly into themixing gun; and

(1. simultaneously de-actuating the pumping means on the first storagecontainer and the pumping means on the second storage container when thedesired amount of the polymer mixture has been dispensed.

. 7. The improvement of claim 6 wherein said first connecting meansincludes a first ball valve and said sec ond connecting means includes asecond ball valve. each of said valves including a ballhaving a bore ofsubstantially the same diameter as, and aligned axially with'the valvebore;

8. Theimprovement of claim 7 wherein the mixing gun is connected to apressurized source of a fluid, in which the polymer mixture is soluble,by a third connecting means including a third valve, in the closedposition, said improvement including the additional steps of:

'e. closing said first ball valve and said second ball valve;

f. moving said third valve to the open position, thereby admitting thesolvent fluid into the mixing gun under pressure, dissolvingsubstantially all of the polymer mixture remaining in the gun, andexpelling the dissolved polymer mixture and solvent from the mixing gun,whereby the gun is clean and ready for subsequent use withoutdisassembling any portion of the mixing gun or connecting temporarylines thereto.

9. An airless mixing gun especially suited for mixing and dispensing thefirst and second reactive components of a high viscosity, urethane-basedadhesive. said mixing gun consisting essentially of:

a. an elongated hollow member having an input end and an output'end,said member defining a mixing chamber and terminating in a nozzle atsaid output end;

b. mixing means located within said hollow member and acting incooperation therewith such that, after the first and second reactivecomponents pass through said hollow member under pressure, the reactivecomponents comprise a generally homogeneous mixture;

c. a body member adjacent the input end of said hollow member, adaptedto have a plurality of valves mounted thereto;

d. a first valve and a second valve mounted on said body member, each ofsaid valves including a valve bore and a ball defining a bore ofsubstantially the same diameter as said valve bore;

e. said body member defining a passage interconnecting each of saidvalves and said mixing chamber such that each of said valves is inpermanent, open communication with said mixing chamber.

10. The mixing gun of claim 9 including a third valve mounted on saidbody member, in permanent, open communication with said mixing chamberand adapted to be fixedly connected to a pressurized source of a solventfluid.

11. Apparatus for mixing a plurality of reactive components and applyingthe mixture, said apparatus consisting essentially of:

a. an elongated hollow member having an input end and an output end,said member defining a mixing chamber and terminating in a nozzle atsaid output end;

b. mixing means located within said hollow member and acting incooperation therewith such that, after the reactive components passthrough said hollow member under pressure, the reactive componentscomprise a generally homogeneous mixture;

c. a body member fixedly mounted to said input end of said hollow memberand adapted to have a plurality of valves mounted thereto; and

d. a plurality of valves mounted on said body member, each of saidvalves having an inlet bore and a pressurized source of one of thereactive components connected thereto and each of said valves having anoutlet bore in permanent, open communication with said mixing chamber,by means of a passageway through said body member.

12. The apparatus of claim 11 including a flush valve mounted on saidbody member, having an inlet bore and a pressurized source of a solventfluid connected thereto, said flush valve having an outlet bore inpermanent, open communication with said mixing chamber, by means of apassageway through said body member, whereby said mixing chamber can beflushed with said solvent fluid without disassembling any portion ofsaid apparatus and without the necessity of temporarily attachingadditional lines or equipment to said apparatus.

13. The apparatus of claim 11 wherein said valves are ball valves inwhich the ball defines a cylindrical bore, of substantially the samediameter as said inlet bore and said outlet bore such that the valveprovides a generally smooth-walled, continuous path of flow for thereactive component.

14. The apparatus of claim 11 wherein said valves are operable to havesaid cylindrical bore oriented axially with said inlet bore and saidoutlet bore and maintain said orientation as the reactive component isintermittently pumped through said valve.

1. Apparatus for mixing a first reactive component and a second reactivecomponent and applying the mixture, said apparatus consistingessentially of: a. an elongated hollow member having an input end and anoutput end, said member defining a mixing chamber and terminating in anozzle at said output end; b. mixing means located within said hollowmember and acting in cooperation therewith such that, after the firstand second reactive components pass through said hollow member underpressure, the reactive components comprise a generally homogeneousmixture; c. a body member fixedly mounted to said input end of saidhollow member and adapted to have a plurality of valves mounted thereto;d. a first valve and a second valve mounted on said body member, saidfirst valve having an inlet bore and a pressurized source of the firstreactive component connected thereto, said second valve having an inletbore and a pressurized source of the second reactive component connectedthereto; e. each of said valves having an outlet bore in permanent, opencommunication with said mixing chamber, by means of a passageway throughsaid body member.
 2. The apparatus of claim 1 wherein said mixing meansis rotatably mounted within said mixing chamber and is driven by anexternal drive means connected to said mixing means by a sealed shaft,such that substantially no air is allowed to enter said mixing chamberduring mixing.
 3. The apparatus of claim 1 including a third valvemounted on said body member, having an inlet bore and a pressurizedsource of a solvent fluid connected thereto, said third valve having anoutlet bore in permanent, open communication with said mixing chamber,by means of a passageway through said body member, whereby said mixingchamber can be flushed with said solvent fluid without disassembling anyportion of said apparatus and without the necessity of temporarilyattaching additional lines or equipment to said apparatus.
 4. Theapparatus of claim 1 wherein said valves are ball valves in which theball defines a cylindrical boRe, of substantially the same diameter assaid inlet bore and said outlet bore such that the valve provides agenerally smooth-walled, continuous path of flow for the reactivecomponent.
 5. The apparatus of claim 4 wherein said valves are operableto have said cylindrical bore oriented axially with said inlet bore andsaid outlet bore and maintain said orientation as the reactive componentis intermittently pumped through said valve.
 6. In a method of mixing afirst reactive component and a second reactive component and dispensingthe resulting highly viscous polymer mixture, the method includingpumping the first reactive component from a first storage container tothe mixing gun, pumping the second reactive component from a secondstorage container to the mixing gun, admitting the first and secondreactive components into the mixing gun, mixing the reactive componentsand dispensing the polymer mixture, the improvement comprising: a.providing a first connecting means such that the first storage containeris in open communication with the mixing gun; b. providing a secondconnecting means such that the second storage container is in opencommunication with the mixing gun; c. simultaneously actuating thepumping means on the first storage container and the pumping means onthe second storage container, thereby forcing the first and secondreactive components directly into the mixing gun; and d. simultaneouslyde-actuating the pumping means on the first storage container and thepumping means on the second storage container when the desired amount ofthe polymer mixture has been dispensed.
 7. The improvement of claim 6wherein said first connecting means includes a first ball valve and saidsecond connecting means includes a second ball valve, each of saidvalves including a ball having a bore of substantially the same diameteras, and aligned axially with the valve bore.
 8. The improvement of claim7 wherein the mixing gun is connected to a pressurized source of afluid, in which the polymer mixture is soluble, by a third connectingmeans including a third valve, in the closed position, said improvementincluding the additional steps of: e. closing said first ball valve andsaid second ball valve; f. moving said third valve to the open position,thereby admitting the solvent fluid into the mixing gun under pressure,dissolving substantially all of the polymer mixture remaining in thegun, and expelling the dissolved polymer mixture and solvent from themixing gun, whereby the gun is clean and ready for subsequent usewithout disassembling any portion of the mixing gun or connectingtemporary lines thereto.
 9. An airless mixing gun especially suited formixing and dispensing the first and second reactive components of a highviscosity, urethane-based adhesive, said mixing gun consistingessentially of: a. an elongated hollow member having an input end and anoutput end, said member defining a mixing chamber and terminating in anozzle at said output end; b. mixing means located within said hollowmember and acting in cooperation therewith such that, after the firstand second reactive components pass through said hollow member underpressure, the reactive components comprise a generally homogeneousmixture; c. a body member adjacent the input end of said hollow member,adapted to have a plurality of valves mounted thereto; d. a first valveand a second valve mounted on said body member, each of said valvesincluding a valve bore and a ball defining a bore of substantially thesame diameter as said valve bore; e. said body member defining a passageinterconnecting each of said valves and said mixing chamber such thateach of said valves is in permanent, open communication with said mixingchamber.
 10. The mixing gun of claim 9 including a third valve mountedon said body member, in permanent, open communication with said mixingchamber and adapted to be fixedly connected to a pressurized soUrce of asolvent fluid.
 11. Apparatus for mixing a plurality of reactivecomponents and applying the mixture, said apparatus consistingessentially of: a. an elongated hollow member having an input end and anoutput end, said member defining a mixing chamber and terminating in anozzle at said output end; b. mixing means located within said hollowmember and acting in cooperation therewith such that, after the reactivecomponents pass through said hollow member under pressure, the reactivecomponents comprise a generally homogeneous mixture; c. a body memberfixedly mounted to said input end of said hollow member and adapted tohave a plurality of valves mounted thereto; and d. a plurality of valvesmounted on said body member, each of said valves having an inlet boreand a pressurized source of one of the reactive components connectedthereto and each of said valves having an outlet bore in permanent, opencommunication with said mixing chamber, by means of a passageway throughsaid body member.
 12. The apparatus of claim 11 including a flush valvemounted on said body member, having an inlet bore and a pressurizedsource of a solvent fluid connected thereto, said flush valve having anoutlet bore in permanent, open communication with said mixing chamber,by means of a passageway through said body member, whereby said mixingchamber can be flushed with said solvent fluid without disassembling anyportion of said apparatus and without the necessity of temporarilyattaching additional lines or equipment to said apparatus.
 13. Theapparatus of claim 11 wherein said valves are ball valves in which theball defines a cylindrical bore, of substantially the same diameter assaid inlet bore and said outlet bore such that the valve provides agenerally smooth-walled, continuous path of flow for the reactivecomponent.
 14. The apparatus of claim 11 wherein said valves areoperable to have said cylindrical bore oriented axially with said inletbore and said outlet bore and maintain said orientation as the reactivecomponent is intermittently pumped through said valve.